Conductivity of leather waste carbonized at various temperature: A challenge to conducting polymers

Abstract

The pigskin leather was carbonized in inert atmosphere at temperatures up to 1200 °C in order to produce conducting nitrogen-containing carbons. The yield of the solid char was close to 30 wt% at 400 °C and remained still above 20 wt% even at the highest temperature. The original morphology of collagen fibres was preserved except for some shrinkage. The changes in the molecular structure were followed by FTIR spectra. Raman spectra reflected the conversion of the biopolymer to carbon. Specific surface area of carbonized products was low, of the order units m2g−1. The four-point setup was applied to evaluate the resistivity of samples as a function of pressure applied up to 10 MPa. The resistivity decreased with increasing pressure and corresponding double logarithmic presentations were linear. Electrical properties were found to be comparable with conducting polymers, such as polypyrrole. The conductivity of the product carbonized at 1000 °C and 1200 °C compressed at 10 MPa reached 5.3 and 11.2 S cm−1, close to the conductivity globular polypyrrole or polypyrrole nanotubes under the same conditions. The biochar obtained after the carbonization of leather waste thus can compete with conducting polymers when it comes to applications relying on electrical properties.